Elastic thread



oct. 13, 1936. F. J, KENNEDY 2,057,577

ELASTIC THREAD Filed sept. 28, 19:54

atented Oct. 13, i936 ATENT FFICE This invention relates to elastic thread of the type useful for .the manufacture of elastic surgical bands or` other similar fabrics. The thread embodying the present invention is a multistrand twisted thread, each strand being characterized by a continuous rubber core of one or more filaments having a single or multiple helical wrapping of fibrous yarns.

In the manufacture of elastic thread, a core of one or more rubber filaments is fed longitudinally in stretched condition while a spool of brous yarn is carried around the core so as to wrap the same with helical turns of yarn. If the wrapped core is then released, it hasa strong tendency to kink and twist. This tendency has made it diflicult to handle such elastic thread in machines for knitting or weaving fabrics. To overcome this kinking tendency, azsecond wrapping of textile yarns is customarily made on the rubber core by passing a second spool of yarn about the core in the opposite direction so that the thread is thus provided with superimposed wrappings in opposite directions. This greatly reduces but does not altogether remove the tenvdency to kink. According to the present inven- YYYYYY -tion, instead o f attempting to offset or compensate for the natural tendency on the part of the single-wrapped rubber core to twist and kink, I put this tendency to use by laying such a strand x along side vof other similar strands and twisting these strands together to form a multi-strand elastic thread. Such a strand can be used without trouble or dimculty, as, for example, in' a machine for knitting or weaving elastic fabrics.

For a more complete understanding of the invention,l reference' may be had to the description thereof which follows, and to the drawing of which Figure 1 shows in elevation a piece of rubber core with a single layer of yarns wound thereon.

Figure 2 shows in elevation a piece of twostrand thread made by twisting together two strands similar to that shown in Figure 1.

Figure 3 shows an elastic thread made of four strands twisted together.

Figure 4 shows'a modified form of the inven- Figure 5 shows a large cord made of a plurality of multiple-strand threads.

The invention may be-characterized in one of its aspects by a multi-.strand thread having two or morensrtrands II) twisted together as illustrated in Figures 2 and 3, each strand having a core Il im Aof one or more filaments of untwisted resilient material, such, for example, as soft rubber. On

each core II is wound a single layer of fibrous yarns I2. While the core II may, if desired, be wrapped with a single yarn I2, it is preferable for economy of time to wrap several threads on the core simultaneously, the threads being fed in 5 side-by-side relation so that they form a single layer covering the core with a iibrous sheath having a uniform thickness equal to the diameter of one of the yarns. As the core is stretched and under tension when being wrapped with the 10 yarns I2, the wrapped core, if released, has a tendency to twist and kink. According to the present invention, this tendency to twist is utilized by bringing together two or more strands I0 each consisting of a resilient core Il wrapped 15 in the same direction with textile yarns I2 as described. These strands are then twisted together. .Y

to form a multi-strand thread such as is illustrated in Figure 2 or Figure 3. The strands are twisted together in a direction opposite to the 20 direction of wrapping of the yarns I2 so that the tendency of each wrapped strand to twist serves to retain the twist of the several strands in the thread. The twisting of the several strands together may conveniently follow immediately upon 25 the wrapping of the individual strands with fibrous yarns.' Thus the twisting tendency of the individual strands is utilized before the strands have had an opportunity to form undesirable kinks. 30

While the threads of two or four strands are shown, by way of illustration, in Figures 2 and 3 of the drawing, the invention is not limited to any particular number of such strands.'

Figure 4 illustrates a modied form of multi- 35 strand thread, each strand I5 having a rubber core I6 and two wrappings I1 and I8 of yarn. If, as shown, these wrappings are wound in opposite directions, the strands will have little tendency to twist or kink. Hence, after the cores 40 I6 are wrapped, I twist the wrapped strands I5 before laying them together to form the thread.

As shown in Figure 5, I may make a heavy elastic cord 2li by twisting a suitable number of multi-strand threads such as are illustrated in 45 Figures 2, 3 or 4, and then twisting together these twisted threads.

It is evident that various modifications and changes may be made in the specific embodiments of the invention herein shown and described, 50 without departing from the spirit or scope of the invention as dened by the following claims.

1. A method of making twisted thread, which comprises for/ming a plurality of strands by wrap- 55 ping yarns helically and in the same direction around a plurality of untwisted cores of soft resilient material, and twisting said strands together in the opposite direction.

2. A method of making twisted thread, which comprises forming aplurality of strands by wrap\l ping yarns helically and in the same direction on a plurality of stretched rubber iilaments whereby each. strand acquires a tendency to twist in the opposite direction, bringing the strands together, and permitting said tendency of the strands to twist them together.'

' of a substantially twist-free core of soi't resilient material with a covering of yarn wrapped helically thereon in one direction only whereby a tendency to twist is imparted to each strand, said tendency being neutralized by doubling in a direction opposite to the direction of wrapping on the cores.

4. A twisted elastic thread comprising a plurality of strands which have been doubled without preliminary twist, each said strand consisting of a substantially twist-free rubber core with a covering of yarn wrapped helically thereon in one direction only whereby a tendency to twist is 'imparted to each strand, said tendency being neutralized by doubling in a direction opposite to the direction of wrapping on the cores.

FRANCIS J. KENNEDY. 

